All growth and development that takes place in a society is dependant on a capable leader and obeying his commands. From the Shia point of view during the occultation of Imam Mahdi in which no one can be in touch with the Imam, the just jurists that possess all qualifications are to assume this responsibility. They should possess other features like piety, justice, taqwa (God wariness), understanding Islam and Jurisprudence, social perspicacity of the era, administrative facilities and adequate ability for leadership. Also they must be pure of bad traits such as: greed, stinginess, covetousness, eagerness for social positions, compromising principles and being weak-willed. Choosing such a person for the critical position of leadership and supervision of the Islamic society is very difficult and few people can make such a choice. On this basis it is mentioned in the Constitution of The Islamic Republic of Iran that God-wary specialists and experts are responsible for this issue that are elected by the people and through the majority of votes. In other words, the leader is indirectly chosen by the people through the Assembly of Experts, because the Assembly of Experts are chosen by the people through the majority of votes and then this Assembly appoints the Supreme Leader through the majority of votes (of the members of the assembly).
Therefore although there is a possibility of mistake but a certain mechanism has been suggested that reduces this possibility to the lowest level. Obviously until it is not proven that the people's choice was wrong, all must submit to their choice.
Having a capable leader and obeying his commands is a critical issue for all societies, and all people agree on this, because not only will there be no order and unity in the society, there will also be no growth and development. From the Shia point of view leading the society is the duty of holy leaders (the prophet and the imams) that have been chosen by Allah to assume this critical responsibility, but during the occultation in which the Muslim society is not in touch with the Imam, this burden is on the shoulders of the just Jurists that possess qualification to be a leader. Imam Sadiq said: "Whenever (a Jurist) rules according to our rule, whoever does not obey him has disrespected the command of Allah and has opposed us, and opposing us is opposing Allah which is as bad as shirk." Sheikh Sadooq has narrated from Ishaq Bin Yaqub through an authentic narration that he said: I asked Muhammad Bin Othman (Imam Mahdi's second ‘specific’ representative during the minor occultation) to give the Imam my letter in which I had asked several difficult questions. The Imam responded with his own handwriting and the following sentences were mentioned in his letter: " ...و اما الحوادث الواقعة فارجعوا فیها الی رواة حدیثنا، فانهم حجتی علیکم و انا حجة الله علیکم.. "  "Regarding the incidents that take place, refer to the narrators of our Ahadith, because they are my Hojjah (Proof) over you and I am the Hojjah (Proof) of Allah over you."
Therefore, because of not being able to communicate with the Imam, it is the qualified jurist, possessing all the requirements that should assume the responsibility of leadership and Wilayyah (Authority) as the Waly Faqih and presiding over the Islamic society during the occultation. Knowing that the multiplicity of decision-makers in society would cause disorder and chaos and leading a society must be done through order and discipline, our intellect concludes that only one person should be recognized as leader, and on this basis everyone, even other jurists, should obey the Waly Faqih. Therefore if a jurist forms a government and assumes its leadership, the other jurists must obey him and they cannot interfere in the decisions that are made by him. But what can we do about the fact that he may make mistakes or misuse his power and authority, because after all, the leader is not infallible? Islam has suggested certain methods in order to reduce the consequences of this possibility, for example it has set a number of required features which one must possess in order to be leader:
1- He must be Mo'men, Just and God-Wary 2- He must be a Jurist well aware of the surrounding circumstances of his time 3- He must possess adequate ability for leadership and be a capable decision maker 4- He must also be pure of bad traits like: greed, stinginess, covetousness, being eager for social positions, compromising principles, being weak-willed, etc. Obviously the most capable person should be chosen as leader from among the qualified individuals.
The next question is how should the leader be chosen and what is the best way to do so?
Knowing that during the occultation of Imam Mahdi no one is going to be directly chosen for this position, it seems that the best way to make a right choice is to act on the opinion of the majority of the people; because although there is a possibility of mistake if people make choices on there own or even together, but if the majority of people make a choice freely and with the required insight and vision, the possibility of mistake is greatly reduced. This mechanism is also employed in today's developed societies. Also, this method is mentioned in the Constitution of the Islamic Republic of Iran as the way to choose the Waly Faqih: “After the demise of the eminent marja' al-taqlid and great leader of the universal Islamic revolution, and founder of the Islamic Republic of Iran, the Grand Ayatollah Imam Khomeini who was recognized and accepted as marja' and leader by a decisive majority of the people, the task of appointing the Leader shall be vested with the experts elected by the people. The experts will review and consult among themselves concerning all the Fuqaha' possessing the qualifications specified in Articles 5 and 109. In the event they find one of them better versed in Islamic regulations, the subjects of the Fiqh, or in political and social Issues, or possessing general popularity or special prominence for any of the qualifications mentioned in Article 109, they shall elect him as the Leader.”
The members of the Assembly of Experts are chosen directly by the absolute majority of people from among expert, god-wary and trustworthy individuals. Therefore considering the fact that the leader (Waly Faqih) is chosen by the Assembly of Experts and the members of this Assembly are chosen by the people, this choice reduces the possibility of mistake to a great extent and can be accurate so that the critical role of leading the Islamic society is assumed by one who possesses all the qualifications at the highest level. In addition to this obligation, the Assembly of Experts is responsible for keeping an eye on his actions, making sure he remains qualified and is fulfilling his duties and whenever they come to the conclusion that he no longer possesses the mentioned qualifications he will be removed from the position and replaced with the appropriate individual.
Based on what was explained one can conclude that the mechanism and procedure of choosing a leader employed by the Islamic Republic of Iran is the best practical method possible. But at the same time if you believe there is a better method that is also practical and can be carried out, let us know so that we can discuss it.
For more information you can refer to the following links:
1- The Conditions of the Waly Faqih, Question 9688 (website: 9679).
2- Choosing the Waly Faqih, Question 786 (website: 845).
3- The Scope of Wilayat Faqih Regarding Other Regions, Question 1439 (website: 1445).
 Wasa’el al-Shia, vol. 1, pg. 67.
 Wasa’el al-Shia, vol. 27, pg. 140.
 For information on this hadith, see: Hadavi Tehrani, Mahdi, Velayat va Diyanat, pp. 94-102.
 Hadavi Tehrani, Mahdi, Velayat va Diyanat, pg. 142.
 With help from Question 786 (website: 845), Choosing the Waly Faqih.
 With help from Question 920 (website: 2975), The Waly Faqih and Infallibility.
 The Constitution of the Islamic Republic of Iran, article 107.